In dental treatment field, a CT X-ray photographing apparatus is used to radiate a given amount of X-ray beams to a set of teeth to be photographed, to measure the amount of X-ray beam radiation by an X-ray sensor, to record the measured data on a memory, to obtain an X-ray absorbing rate of each point of the photographed region by a computer, and to reconstruct the obtained absorbing rate to an image. A panoramic X-ray photographing apparatus performs tomography while being rotated along a needed track in accordance with the shape of a dental arch, thereby performing tomography. A cephalometric X-ray photographing apparatus is mainly used to photograph a patient s head so as to perform orthodontic treatments or orthognathic surgery.
Using such the panoramic X-ray photographing apparatus, the CT X-ray photographing apparatus and the cephalometric X-ray photographing apparatus, a panoramic image, a CT image, and a cephalometric image can be obtained. If the images being photographed in a plurality of modes are to be obtained at once, however, they should be photographed individually by using the respective X-ray photographing apparatuses, which is actually cumbersome. In order to remove such the inconveniences in use, thus, there are proposed a variety of X-ray photographing apparatuses each providing the panoramic image, the CT image, and/or the cephalometric image in a single system. For example, a panoramic and CT X-ray photographing apparatus provides both of the panoramic image and the CT image, and a panoramic and cephalometric X-ray photographing apparatus provides both of the panoramic image and the cephalometric image. Like this, X-ray photographing apparatuses that provide images to be photographed in a plurality of modes at the same time have been proposed and developed.
However, the conventional X-ray photographing apparatuses should have a separate mode conversion means so as to obtain the images photographed in the plurality of modes at once, and also, the mode conversion has to be manually performed in accordance with the mode to be photographed, which makes it inconvenient to use.